Introduction: Tannase is a crucial enzyme that finds wide applications in the pharmaceutical industry, feed processing, and beverage manufacturing. Although extensive studies have been conducted on tannases from fungi and bacteria, reports on tannases exhibiting favorable pH stability are relatively limited.Methods: In this study, a tannin-degrading strain Debaryomyces hansenii was screened to induce tannase production, and the corresponding tannase coding gene TANF was successfully cloned and expressed in Yarrowia lipolytica. SDS-PAGE analysis revealed that the purified TanF tannase had a molecular weight of approximately 70 kDa.Results and Discussion: The enzyme demonstrated optimal activity at 40°C and retained over 80% of its activity in the range of 35°C–60°C. Of particular interest, TanF exhibited remarkable enzyme activity at pH 5.0 and retained more than 70% of its relative activity across a wide pH range of 3.0–8.0. Furthermore, TanF exhibited broad substrate specificity for gallate esters. The final gallic acid production by TanF from tannic acid achieved 18.32 g/L. Therefore, the excellent properties TanF has been demonstrated to be an efficient tool for the preparation of gallic acid.

The enzyme α-isopropylmalate synthase (α-IPMS) catalyzes the first step of L-leucine biosynthesis and is regulated via feedback inhibition by L-leucine. The gene of α-IPMS variant from strain ARTP-L04 was cloned and sequenced. Interestingly, amino acid mutations of Gly92Asp, Ile162Val, Arg494His and Gly526Asp occurred in the α-IPMS variant. The enzyme of α-IPMS variant was characterized, and exhibited higher resistance to feedback inhibition by L-leucine. In the presence of 20 mM L-leucine, the activity of the α-IPMS variant was still retained at over 50%. The α-IPMS variant almost removed feedback inhibition by L-leucine, while there was no significant difference in specific activities of the α-IPMS variant and wild-type α-IPMS. For the α-IPMS variant, the capacity to overproduce L-leucine was evaluated by recombinant Corynebacterium glutamicum strains. Interestingly, expression of the α-IPMS variant could significantly enhance L-leucine production, especially co-expressed with acetohydroxyacid synthase (accumulating 7.79 g/L L-leucine). Collectively, our findings provided valuable insights into further development in genetic engineering for L-leucine production.

Tropaeolum majus (nasturtium) is an important ornamental and medicinal plant due to its colorful flowers, shield-shaped leaves, and richness in mineral elements and bioactive compounds. However, the key genes related to these important biological traits, as well as their expression patterns and functions, remain obscure. In this study, to choose appropriate reference genes for quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) analysis, we screened 14 candidate genes from the transcriptome of T. majus and evaluated their expression stability. Through evaluation with four commonly used algorithms (geNorm, NormFinder, BestKeeper, and RefFinder), EXP1, EXP2, and TUB6 were found to be the most stably expressed genes among different organs, while EXP1 combined with CYP2 was identified as the optimal reference gene combination for seeds at different development stages. For all the tested samples, EXP1, EXP2, CYP2, and ACT2 were the most suitable reference genes. Moreover, the target gene KCS11 involved in very-long-chain fatty acid biosynthesis was employed to confirm the most and least stable reference genes in different organs, seeds at different development stages, and all the tested samples. The expression profiles of KCS11 were similar, with minor differences based on the analysis of different stable reference genes (either alone or in combination), while the expression profiles were diverse and the relative expression level was overestimated when using the least stable ones. These results suggest that the appropriate selection of reference genes is critical for the normalization of gene expression. Furthermore, the reference genes screened in this study will greatly improve the accuracy of the qRT-PCR quantification of candidate genes involved in the many biological characteristics of nasturtium.

Enzymatic alginate oligosaccharides were proved with various biological activities. Developing robust alginate lyase with high production is essential for its industrial application. In this study, a novel alginate lyase gene, AL07, was successfully screened and expressed in Pichia pastoris, and its characteristics were characterized. The secreted alginate lyase has a molecular weight of approximately 40.0 kDa and an activity of 45.4 U/mL. AL07 exhibits superior biological activity at pH 7.0 and 40 °C, with a preference for polyG substrates. Notably, the enzyme exhibits more than 60% relative activity over a pH range of 5.0 to 10.0. AL07 is also independent of ions and exhibits salt tolerance properties. The main degradation product of AL07 is DP2 oligosaccharide. Using AL07-based enzyme cocktail, Laminaria japonica can be degraded within 120 min. Therefore, AL07 has been demonstrated to be an efficient tool for the preparation of alginate oligosaccharides and the degradation of L. japonica.

Oily skin is a prevalent, cosmetically troubling condition. This study investigated the effects of a topical cream with 3% lactic acid ferment lysate VHProbi ^® MixP for ameliorating oily skin symptoms. A 60-day pilot trial enrolled 42 oily-skin participants, who applied the cream twice daily. Standardized non-invasive tools and imaging systems measured sebum production, porphyrin levels, pore appearance, transepidermal water loss (TEWL), hydration and texture at baseline, day 30 and day 60; 16S rRNA gene sequencing was used for hypothesis-generating analysis of the facial microbiota. By day 60, sebum, porphyrin levels and pore size decreased significantly (31.44%, 44.60% and 25.03% respectively), while hydration and texture improved (63.68% and 38.43% respectively). Hypothesis-generating microbial analysis identified elevated α-diversity and shifted bacterial composition, with reduced Staphylococcus spp. and Cutibacterium spp. and increased Streptococcus spp. Correlation analysis indicated associations between topical application of the cream and reduced sebum secretion, as well as modulated cutaneous microbiota composition. In conclusion, topical application of VHProbi ^® MixP is associated with reduced facial hyperseborrhea, increased epidermal hydration and modulated cutaneous microbial community structure, and may hold potential as an ingredient for oily skin care.